Overview of Ocular (Eye) Discharge in Dogs
Ocular discharge is a common sign of eye disease in dogs. Abnormal discharge may develop suddenly or gradually. The discharge may be watery, mucoid (gray, ropy), mucopurulent (yellow-green, thickened) or bloody. In general, the more discharge present, the more serious the disease.
Causes of Canine Eye Discharge
Obstruction of tear drainage due to abnormal tear ducts or tear duct openings
Excessive production of tears by the tear glands from irritation or inflammation of the surface structures of the eye, or from pain in or around the eye. Examples include:
Keratitis (inflammation of the cornea)
Blepharitis (inflammation of eyelids)
Defects or abnormalities in the eyelids
Lens luxation (displacement)
Uveitis (inflammation of the iris and blood vessel layers within the eye)
Keratoconjunctivitis sicca or dry eye syndrome
Infection on the surface of the eye, or in association with generalized infections or illness
Diagnosis of Ocular Discharge in Dogs
Certain diagnostic tests are essential to determine the precise cause of the ocular discharge, including:
Complete ophthalmic examination of the eyelids, cornea, conjunctiva, the front and back chambers of the eye
Schirmer tear test
Fluorescein and possible rose bengal staining of the cornea
Tonometry to measure the pressure within the eye
Additional diagnostic tests are required to diagnose some causes of ocular discharge. These may include:
Complete physical examination
Cytology or complete cell analysis of samples collected from the eyelid margins, cornea or conjunctiva
Flushing of the openings where tears drain away from the eye to ensure they are patent (open)
Culture of discharge from the eye to determine the presence of bacterial infections
Complete blood count (CBC) and serum tests to determine the presence of any related systemic problems
Possibly skull X-rays to determine the presence of a problem in the space behind the eye or in the sinuses
Possibly specialized imaging tests such as dacryocystorhinography, an X-ray study of the tear drainage system), computed tomography (CT) scan, and magnetic resonance imaging (MRI)
Treatment of Ocular Discharge in Dogs
Successful therapy relies on obtaining an accurate diagnosis. Do NOT use human over-the-counter eye drops that are designed to treat red eyes.
Gently clean away any eye discharge with a warm moist cloth as needed until the cause of the problem is identified. Do not allow your pet to rub or self-traumatize the eyes.
Do not delay in bringing your pet to your veterinarian for examination as some causes of excessive ocular discharge are potentially vision threatening and require immediate medical attention. Do not administer human prescription eye medicine or even over-the-counter medicines such as Visine® or other topical solutions intended to reduce eye redness to your pet. The underlying cause for the problem must be properly addressed.
As a temporary measure, the eyes may be flushed or the eyelids cleansed with sterile saline solution.
In-depth Information on Ocular Discharge in Dogs
It is important to understand that any source of ocular irritation or pain can cause ocular discharge. Abnormal ocular discharge is not diagnostic of any one disease or disorder. In the simplest sense, ocular discharge represents the response of the eye to an irritation, injury, or an inability to drain tears or secretions properly. The exact cause can only be determined by a careful examination and appropriate diagnostic tests.
Observe your pet for any change in eye discharge. A minor amount of eye discharge is normal; however, any change from what is normal for your pet may be significant.
Decisive therapy for ocular discharge depends on identifying the exact cause of the problem. There are numerous possible inciting causes for ocular discharge. It is essential to distinguish a specific cause to provide the appropriate therapy.
Among the potential causes of ocular discharge are the following disorders:
Cilia (eyelash) disorders such as distichiasis, which are eyelashes that grow out along the edge of the eyelid and rub on the cornea; ectopic cilia, which are eyelashes that grow out from the inside of the eyelid rub and against the cornea; and trichiasis, which are lashes on the outer eyelids or face that are long enough to rub the eye.
Conformational eyelid defects such as inward rolling of the eyelids (entropion), outward rolling of the eyelids (ectropion) and congenital absence of a portion of the upper eyelid (eyelid agenesis).
Inflammation of the eyelids (blepharitis) or inflammation of the Meibomian glands within the eyelid margins from an immune-mediated disease, or a bacterial, fungal or parasitic infection
Prolapse (protrusion) of the tear gland of the third eyelid, often referred to as “cherry eye”
Tumors of the external eyelids and the third eyelid
Deformities or wounds of the third eyelid
Congenital deformities of the tear drainage pathway, including narrowing or closure of the holes in the eyelids the tears drain through (imperforate puncta)
Inflammation, infection or foreign material within the tear duct drainage system (dacryocystitis) obstructing the drainage of tears away from the eye
Keratoconjunctivitis sicca (dry eye syndrome)
All forms of conjunctivitis
Traumatic scratches, lacerations or ulcerations of the cornea, conjunctiva and eyelids
Trauma to the nose, palate or bones of the face around the eye
Certain forms of inflammation of the cornea (keratitis)
Certain congenital defects of the cornea and conjunctiva such as a dermoid, or a mass containing skin and hair
Anterior uveitis, which is inflammation of the iris and surrounding tissues in the front portion of the eye
Glaucoma, which is sustained elevation of pressure within the eye
Lens luxation or dislocation into the front chamber of the eye
Inflammation, infection, trauma, or tumor development in the soft tissues around the eye
Infection and abscessation of the roots of the back upper teeth
Complete medical history and physical examination
Complete ophthalmic examination including a Schirmer tear test to determine if tear production is normal, elevated or reduced; fluorescein staining of the cornea to detect surface defects, ulcers and erosions; tonometry to measure the pressure within the eye;, and examination of the interior of the eye under magnification. Your veterinarian may refer your dog to a veterinary ophthalmologist for detailed evaluation of the eye using specialized instrumentation.
Cytology (cell analysis) of samples collected from gland openings in the eyelid margins or from the cornea and conjunctiva
Flushing of saline through the tear ducts to ensure they are open
Complete blood count (CBC) and serum tests to identify any related problems.
Initial test results and/or lack of response to initial treatments may necessitate further testing:
Culture of material from infected areas
Polymerase chain reaction (PCR) and immunofluorescent antibody (IFA) tests on samples collected from the conjunctiva and cornea to detect certain viral infections such as distemper virus
Skin cell scrapings from the eyelid or eyelid margin to help determine the presence of parasitic infection, fungal infection, cancerous disease or bacterial infection
A fine-needle aspirate (FNA) of any solitary mass/tumor around the eye
Serology testing for systemic fungal infections, toxoplasmosis and tick-borne diseases
Nasal endoscopy ( the direct visualization of the deep structures within the nasal passages using a scope) when nasal cavity diseases are suspected
Biopsy (tissue sample) collected via endoscopy, pinch biopsy needles, or scalpels of any deep abnormal tissue around the eye
Ultrasonography of the eye and surrounding soft tissues
Skull X-rays to identify fractures, diseases of the sinuses, and bony tumors of the head
Dacryocystorhinography, a specialized X-ray study of the tear duct drainage system
Computed tomography (CT) scan or magnetic resonance imaging (MRI) to identify problems within the eye, around the eye, within the nose and sinuses, the bones of the face or the brain
Treatment will depend on the underlying cause eye discharge.